The surfacing of bacterial resistance to a number of antimicrobial agents such as beta-lactam antibiotics, macrolides, quinolones, and vancomycin is becoming a major health problem worldwide (Trends In Microbiology, 1994, 2, 422-425). The most significant problem in clinical practice is the increase in incidence of methicillin-resistant Staphylococcus aureus (MRSA) infections. At present, the only effective treatment for multiple resistant MRSA infections is vancomycin. However, there are a number of reports of emerging vancomycin resistance in some MRSA isolates (Antimicrobial Agents and Chemotherapy, 1998, 42, 2188-2192). Another group of clinically relevant multiple drug resistant bacteria that has emerged recently is Enterococci, some of which also exhibit vancbmycin resistance. The appearance of vancomycin resistant Enterococci (VRE) infections has forced a dilemma upon physicians. Combinations of Linezolid, an oxazolidinone compound, and streptogramin are the new drugs of choice for treating MRSA infections. However, resistance to these oxazolidinone (Clinical Infectious Diseases, 2003, 36, supplement 1, S11-S23; Annals of Pharmacotherapy, 2003, 37, 769-74) streptogramin combinations (Current Drug Targets Infectious Disorders, 2001, 1, 215-25) and various glycopeptides (Clinical Infectious Diseases, 2003, 36, supplement 1, S11-S23) require expanded development of agents with alternative targets or modes of action. The mounting resistance of the important community acquired pathogen Streptococcus pneumoniae to penicillin and other antibacterials is also becoming a global health problem. Multi drug-resistant strains of Mycobacterium tuberculosis have surfaced in several countries. The emergence and spread of resistant nosocomial and community-acquired pathogens is becoming a great menace to global public health.
There is an urgent need to discover new compounds, which can be used as drugs to treat patients infected with bacteria, particularly the multi drug resistant bacteria such as MRSA and VRE.